1. Field of the Invention
The present invention relates to indicators used for centering parts, and in particular, for locating and centering the bores on parts in relation to an axis that is to be used for boring.
2. Description of the Prior Art
In the prior art there are a wide number of dial indicators presently on the market, and also various micrometers which provide indications from radially extending buttons which are linked to a dial indicator in a desired way.
Dial indicators are well known measurement instruments, which have a dial face on which indications of movement of an indicator button is displayed by movement of a needle. Usually the dial face is capable of being set to a zero reading by moving the dial face without adjusting the needle. The needle responds to movement of the indicator button.
A form of prior art retractable dial bore gauge is shown in U.S. Pat. No. 4,045,877. This device has a bell crank operated external gauge, operating through a link to engage the indicator button of a dial indicator that is remote from its actuator. The linkage has many moving parts, which is a drawback, and in particular where there are a number of pivots and bearings, wear can easily become a problem.
Additionally, an adjustable bore gauge is shown in U.S. Pat. No. 3,302,295. The bore gauge in U.S. Pat. No. 3,302,295 has a range extension button that extends radially and permits the gauge to be used in different bore sizes, and it includes a remote dial indicator for indicating the bore size.
U.S. Pat. No. 2,606,370 shows a conventional inside micrometer which has a radially extending pin, but which is mechanically actuated with external numerals that indicate the size of the bore in which the remote feeler is placed.
A line bore gauge is shown in U.S. Pat. No. 4,338,726, and this requires a set up utilizing bearings mounted in the crank shaft bearing seats, and includes a dial indicator slidably mounted on a shaft passing through the bores to be measured. The dial indicator slides along the shaft and engages the inside surfaces of the bores.
U.S. Pat. No. 4,265,026 also shows an internal measuring device utilizing a dial indicator, and a remote pin operating through a linkage and inclined plane actuator. There is no mechanism to permit presetting the device in the present invention, and there is no teaching of utilization of the indicator in combination with an external micrometer as shown herein.
U.S. Pat. No. 4,211,014 shows a device for inspecting bores as well, as does U.S. Pat. No. 4,170,831. These devices do include indicator dials, and linkages for connecting the dials to remote feelers or indicator pins, and generally represent the state of the art.